Optophone



A. BARR, W. STROUD AND E. E. F. DALBE.

OPTOPHONE.

APPLICATION FILED NOV.26,19I9.

Patented Aug. 24, 1921) (25 jizvevzin Jirchibaldfiarr mlivla1wjfroua gdmcuza fawarizarmrdfllfie UNITED STATES PATENT OFFICE.

ABCHIBALD BARR AND WILLIAM STROUID, or ANNIESLAND, GLASGOW, ScoTLAND, AND EDMUND EDWARD FOURNIER DALBE, or LoNDoN, ENGLAND, ASSIGNQRS To BARR AND STROUD, LIMITED, or GLASGOW, scoTLAND.

QPTOP IONE. I

To all whom it may concern:

Be it known that we, ARGHIBALD BARR and WILLIAM STROUD, subjects of the King of Great Britain and Ireland, and both of Caxtonstreet Anniesland, Glasgow, Scotland, and EDMUND EDWARD FOURNIER DALBE, a subject of the King of Great Britain and Ireland, and of 10 St. James Terrace, Regents Park, London, N; W., 8, England, have invented new and useful 1mprovements in Optophones, of which the following is a specification.

In an optophone as hitherto constructed by one of the present applicants, a ser es of intermittently luminous dots, having d fferent frequencies of intermission, within the range of ordinary musical notes, is pro jected upon a printed page to .be read b a blind person, by means of the ear. he dots, which lie in a line at right angles, or nearly so, to the line of printing, are caused to pass along the line with a more or less uniform motion, either by moving the page or by moving the optical system. The light reflected. from the page is received on a sensitive tablet composed of a substance, the electrical conducting properties of which alter under the action of light, such for example as selenium, placed in circuit with a battery (or other source of current), and a telephone, with the result that when a dot is received on a black portion of the printed surface, the telephone is silent as regards the Sound corresponding to the periodicity of that dot, whereas When it falls upon a white portion a musical note is produced in the telephone of a frequency corresponding to that of the intermissions of the dot. The effect thus produced may conveniently be termed white sounding.

The improvement, which is the subject of the present invention, consists in reversing the action above referred to, so as to produce silence when the whole of. the series of dots falls upon a white surface, and on the other hand, to produce a sound composed of the frequencies of all the luminous dots which fall upon a black surface. The effect thus produced may conveniently be termed black sounding because the black letters themselves cause sounds to be produced varying with the shapes of the letters as the dots pass along the line and a blind person identifies the letters by these sounds instead of Specification of Letters Patent.

identifying them by means of the sounds produced by the white interstices in and be intermitted light, one (hereinafter referred Patented Aug. 24, 1920. Application filed. November 26, 1919. Serial No. 340,745. i

to as the primary tablet) being exposed to the i intermitted light from the white portions of the paper sur ace, the other (hereinafter referred to as the secondary tablet) being continuously exposed to the intermitted light,

. and connecting the two tablets with a telephone and batteryin such a way that the effect of the intermittent light on one tablet balances the effect of the intermitted light on the other when a white surface is exposed and so produces silence in the telephone in that case. Thus no sound (or very little sound) is produced in the telephone untilone or more of the luminous dots falls upon a black (or a comparatively non-reflecting) surface of the printed page. When one or more of the dots falls on a black portion of the page the balance between the actions of the two tablets is destroyed and is not restored until a white portion of the surface of the paper is again presented to receive the whole series of luminous dots. The balance between the actions of the two tablets ma be obtained by any of the electrical metho s hitherto used for producing a'zero current in one element of a network of conductors of. variable resistance. The two tablets may, for example, be inserted in two branches of what is known as a Wheatstone bridge arrangement and balanced by adjusting two other resistances so as to produce a zero current in the branch containing the telephone.

to the wire joining the two tablets, and on the other hand to a junction between two cells, or sets of cells, of the battery, the connection being made at such part of the battery as will cause no current or very little current to pass through the telephone when white paper 'is exposed to the dots.

.In any of these electrical devices the primary tablet will be exposed to the light diffusely reflected from the page, and the'sec.

ondary tablet will be exposed to a small por tion of the intermitted light. carried off at creased or reduced by varying the effectiveness of a reflector which takes up a part of the intermitted light, or by varylng the distance of the secondary tablet, or by varying the obliquity at which the li ht falls upon the secondary tablet, or again I y interposing a semi-transparent substance between the light and the secondary tablet.

Examples of construction will now be shown in connection with the drawings in which Figure 1 is a sectional elevation of the optical and certain mechanical parts of one form of optophone. Fig. 2 is a plan of the mechanical parts shown at the lower portion of Fig. 1. Figs. 3 and 4 are elevations illustrating alternative modifications of a part of the optical system, while Figs. 5, 8 and 9 are sectional elevations illustrating different methods of exposure for the secondary tablet. Figs. 6 and 7 are diagrams illustrating alternative arrangements for the electrical circuits.

In Fig. 1 there is shown a disk 1 (shown in plan in Fig. 2) which can be set in rapid rotation b means (say) of an electrical motor. T is disk has a series of perforations, usually equally spaced, in (say) five concentric circles, the number of perforations being different in each circle just as in an ordinary acoustical siren. Below the disk 1 is placed an incandescent lam 2 with straight filament arranged 'radiilly. Above and below the disk we may place screens 3 with radially placed slots, al-

though either or both of these may be dis- 'pensed with. 4 is a converging lens, while 5 and 6 are additional converging lenses for producing a very small image 0 the incandescent filament at the top surface of a glass plate 8 upon which the printed page is laid face downward, the lines of words being perpendicular to the paper in Fig. 1. Between 6 and 8 there is placed the primary tablet 7, in which an aperture is formed to enable the light to pass through, and, when a printed page is in position on the glass plate 8, be reflected from the white portions of the page angularly downward ontothe top surface of tablet 7, the top surface being the only part of the tablet accessible to light. Thus, with the tablet 7 connected in series with a source of current and a telephone, an instrument comprising these parts only would constitute a white sounding optophone.

According to the present invention, in the method illustrated at Fig. 1 we insert a concave lens 10 in the main beam of intermitted light in an oblique attitude, so arranged that light reflected from the surface of 10 is directed to fall on a secondary tablet 17. In Fig. 3 the concave lens 10 is replaced by a concave-convex lens 11, the surfaces being such that light reflected from both surfacescan be utilized in the formation of the image, while in Fig. 4 a plano convex lens 12 is shown acting by reflection from its upper surface. It is not necessary that an image of the filament shall be formed upon 17 unless the size of the sensitive portion of the tablet is comparable with the dimensions of the source of light. If the sensitive portion of the tablet 17 has fair dimensions there may be no need to form a real image. In such a case the lens 10, 11 or 12 may be replaced by a plane plate of glass.

In the case of Fig. 5 there is no attempt to form a real image upon the secondary tablet which is there represented as in the form of a cylindrical rod 18 with selenium upon a portion of its surface, say in the form of alongitudinal band between two longitudinal conducting strips. The rod 18 may be arranged capable of angular adjustinent, say,"about its axis, whereby the light may be cau'sedto fall more or less obhquely on thesensltlve portion, so as to obtain variations in the magnitude 'of the effect produced by the light, such variations a portion of the beam and reflects it on to the secondary tablet 17.

In Fig. 9 another arrangement is shown inwhich the secondary tablet 17 is illumi nated by portions of the intermitted light that would not enter the main optical system of the instrument, A semi-transparent screen 25 may be interposed .to cut down the amount of light and may be used for adjusting the effectiveness of the light upon the secondary tablet 17 so as to effect the required balance when the main beam falls.

upon a white surface.

The primary and secondary tablets are connected in electrical circuits associated with a telephone in some suitable manner, for example, in the manner shown in Fig. 6 or that shown in Fig. 7. In these figures, 20 designates a telephone, 7 the primary and 1-7 the secondary tablet.

mitted light 2. An optophone having means by which The -ba1ancingc theeiiects of the interu on the two .tablets 7, 17, so far as their 'eiibcts on the telephone 20 are concerned, jmay further be effected, partially or wholly, by variation in-theelectrical resistance of the circuits. I

In-Fig. 6 there is represented an ordinary 'Wheatstone bridge circuit in which the elecand 17, when ptophone and trical eflects of thetablets 7 placed .in position in the, -o exposed to the intermitted hght, are balanced by adjustment of one or other or both of the resistances 21, 22. Fig. 7 shows an alternative arrangement of circuit in which the 'balancin is effected rou hly by shifting one .termlnal of the telep one 20 along the cells of the battery, while the fine adjustment is effected by shifting'the other I I terminal over the resistance 23 until a balance is obtained. I

Weclaimao 1. .An optophone having means by which a series of intermittently luminous beams having different frequencies of: intermission are produced, a primaryv and a secondary sensiftlve tablet each composed of a substance the electrical conducting properties of which alter .under the action of light, means forsnpporting a printed page,the printed pa e having .light reflecting and comparative non-reflectmg surface portlons, means for ontothe secondary series of beams, the surface of the paper intermittently luminous dots of the whole series, the primary tablets being arranged to receive the light reflected from the paper, a source of electricity, two circuits one containing the rimary tablet the other the secondary tabet, and a telephone, for the purposes set a series of intermittently luminous beams having, different frequencies of intermission are produced, a

primary and a secondary sensitive tablet each composed of a substance the electrical conducting properties of which alter under means for supporting a E printed page aving lig t reflecting and comparativel non-reflecting surface portions, means or' reflecting continuously onto the secondary tablet port ons of'thelight of the action of light, rinted page, the

are produced, a

secondary ta .axisof the system to pass throu h and the whole series of beams jecting onto the surface of mittently luminous dots of the primary tablet being'arranged to receive the 'ght reflected from the paper, a source of electricity, two circuits one containing the primary tablet the other the. secondary tablet, and a telephone, forth. I I v 3. An optophone having means by which a series of intermittently luminous beams having difierent frequencies of intermission primary and a secondary sensitive tablet each composed of a substance the electrical conducting properties of which alter under the action of light, means for supporting a printed page, the printed page having lig t reflecting and comparatiw'ely non-reflecting sujrface portions a lens or lenses for pro'ect-ing continuous y onto the secondary tablet portions of the light of the whole series of beams, means for projecting onto the surface of the paper intermittently luminous dots of the whole series, theprimary receive the light reflected from the paper, a source of electricity, two circuits one containingthe rimary tablet the other the let, and a telephone, for the means for pro: the paper mterthe whole series,

purposes set forth. I 4. An optophone consisting of a lamp a plate of glass, an o tical system located between the lamp' ans the plate of glass, the o tical system being normal to the surface of I disk located near the lamp having conc'entric circles of perforations arranged to intersect the li ht enterin the optical system, a primary ta let locate between the optical system and the late of glass having an aperture for the light directed b the optical avmg sensitive surface accessib e to. light resented toward the face of the plate 0 glass, a

secondary tablet located outside the opticalsystem, means located between the optical for the purposes set I tablet being arranged to the plate of glass, arotatable let the other the. secondary tablet, and a' p e, for the purposes set forth. .mcmmnnrmn.

-' WILLIAM STROUD.

EDMUND EDWARD FOURNIER D'AI IBE. 

